This invention relates to a sheet feeding apparatus for feeding sheets one at a time from a sheet stack. More particularly, to a vacuum corrugation feeder that is not dependent on stack height and has unlimited stack capacity.
A need has been shown for the flexibility of medium to small copiers to be able to feed at least 500 sheets of 20 lb. paper with vacuum corrugation feeders such as described in U.S. Pat. Nos. 4,269,406 and 4,411,417 which are incorporated herein by reference. With these paper feeding devices, a stack of paper is substantially horizontally supported which makes it difficult for air to enter between the respective sheets in the stack. Since the bottom sheet in the stack is the first sheet to be fed and is in intimate contact with the next adjacent sheet there is a potential for double feeding. the main problem is how to relieve the force on sheet one of a stack (feeding from the bottom) by the most efficient and reliable method taking into consideration machine energy restrictions.